In partnership with: The Friends of the Utah Avalanche Forecast Center, Utah Department of Public Safety Division of Comprehensive Emergency Management, Salt Lake County, and Utah State Parks
Tuesday, March 18, 2003
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Good Morning. This is Bruce Tremper with the
Last night it continued to
snow with the Cottonwood Canyons picking up another 5-7 inches of 10 percent
water weight snow. This makes 10-13
inches of snow in the past 24 hours. The
For a welcome change, yesterday’s avalanche activity remained just within the new snow as easily-triggered, shallow, soft slabs created by wind deposits. Between three different parties of backcountry skiers in Days and Silver Fork, they were able to trigger perhaps 15-20 of these sensitive wind slabs, mostly intentionally, but occasionally unintentionally. They were breaking mostly 6-8 inches deep, occasionally up to a foot and were 50 to 100 feet wide but one was as much as 250 feet wide. These kinds of fresh, soft wind slabs are much safer to deal with than the monster, deep avalanches we have had for most of the season because fresh, soft slabs tend to be very sensitive, so they tend to break at your feet instead of up above you and they are soft enough to allow for an easier escape. Still they can certainly be dangerous if you’re not prepared. They can easily slam you into trees or burry you in a deep depression such as a gully. (I have details on these slides in the usual locations at 801-364-1591 and at www.avalanche.org – click on Salt Lake, then on Advisories, then on List of Avalanches).
Today you can expect to find
similar, widespread, soft, easily-triggered wind slabs on any slope around 35
degrees or steeper with recent deposits of wind drifted snow. Also, there is a slight density inversion in
the overnight snow, so you may be able to trigger some soft slabs even in non
wind affected terrain. Finally, don’t
forget about our season-long horror story of deep, large avalanches breaking
into faceted snow buried deep in the snow pack.
With all this additional water weight, it’s sure to reactivate a few of
these lurking monsters, mostly on steep slopes with a shallow snowpack above
9,500’. Also, a shallower, soft slab
avalanche may step down into these deeper weak layers as it descends. Today, be sure to wa
Bottom Line (SLC,
Today there is a MODERATE danger of human triggered avalanches on slopes steeper than 35 degrees with recent wind drifts. On slopes with wind deposits more than a foot deep, the danger is CONSIDERABLE. There is also a MODERATE danger of triggering deeper avalanches on slopes above 9,500 feet that face the north half of the compass plus east facing slopes, especially ones with a shallow snow pack.
Bottom Line: (
The huge low pressure center
is now over
The weekend looks nice.
As a special treat the more scientifically inclined avalanche nerds out there, our own Ethan Greene will be giving an advanced-level avalanche talk tonight called the “science of avalanches.” This will be at at REI, which is on 3300 south just off the 215 east side belt route.
To report backcountry snow and avalanche conditions, especially if you observe or trigger an avalanche, please leave a message on our answer machine at (801) 524-5304 or 1-800-662-4140, or email to [email protected] or fax to 801-524-6301. The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.
I will update this advisory by on Tuesday morning.
Thanks for calling!
For an explanation of avalanche danger ratings: